First time Dyno. Slight Problem

[95ImpySS]

A local up and coming shop had a Dyno day last night. So I took the car out to see what it would turn on a baseline mail order tune. Ended up making 350WHP and 342LbFt. Not to shabby I think. More to be had. I have a slight issue with the engine up top. Around 5200-5500RPM the car hesitated. I felt it on the street but the dyno graph really puts it out there. Anyone have any ideas what it could be? Shop said Opti, but I think its tune related. Whats the LTx community have to say? I can also supply Datamaster datalogs of each run to whom ever would like to take the time to look them over

Thanks in advance
Brad

Here is the dyno sheet:

http://i1093.photobucket.com/albums/i428/95ImpySS/scan0001.jpg

[popo8]

I get soooo pissed off when OPTI is tge first thing blamed.....

3 diff motor combos... a gaggilion optis and me and two of my friends all with different optis and builds have the same idsue in the same rpm range...... So opti is not the answer!!!!


http://img.tapatalk.com/ae31b287-3d3f-e9a3.jpg

Is where it stumbled before.... new shop swears its cause its running outta fuel. Hsving fuel system upgraded to see where we are afterward....

If its the opti... then my dynaspark... my friends delco.... my other friends msd are all bad at the same time!


RANT OVER.....


lol....sorry

[95ImpySS]

J O Y. I had a feeling this would be a hard to find issue. I know the tuner is going to have a fit. Guess I'll just have to play around with the tune in the right areas to see if rich/lean/+or- timing solves the problem.

Thanks for the reply PoPo. Keep me posted if you solve or hear anything regarding this problem

[popo8]

I def will and sorry for the rant....

I hope u can c we are stumbling in very similar areas of the graph.

[95ImpySS]

No worries on the rant. I have I feeling I'll be ranting right with you here soon. Were having issues in the same RPM range. Whats odd for me, is that mine seemed to go in an upward direction rather than down. I wanted to ask the guy running the dyno to clarify, but the place was packed and they were churning cars out left and right. As well as it was pretty hard to get the car to dyno right. I had no time to modify shift points to hold a gear. Had to start the dyno in 3rd above 3500 RPM to prevent downshifting.

What was your Air Fuel reading like during the pull? I would assume, if it went rich, it would be an ignition/combustion problem. If it went lean, I would be a fueling problem....

[meissen]

Post up the data logs if you don't mind. I'm not the best at reading the logs and interpreting them, but maybe I might see something.

[MoeHorsePower]

A local up and coming shop had a Dyno day last night. So I took the car out to see what it would turn on a baseline mail order tune. Ended up making 350WHP and 342LbFt. Not to shabby I think. More to be had. I have a slight issue with the engine up top. Around 5200-5500RPM the car hesitated. I felt it on the street but the dyno graph really puts it out there. Anyone have any ideas what it could be? Shop said Opti, but I think its tune related. Whats the LTx community have to say? I can also supply Datamaster datalogs of each run to whom ever would like to take the time to look them over

Thanks in advance
Brad

Here is the dyno sheet:

http://i1093.photobucket.com/albums/i428/95ImpySS/scan0001.jpg

do you have an MDS Box? Reason I ask, is that I have seen this many times for LT's at that same RPM but it was on builds that had no MSD, when installed, the dip went away, mine included. If you have a box, then it could be possibly in the tune for that area,

[BlackWidowSS]

I had an MSD box for my dyno and a mallory hyfire box now and I feel no stumble nor do I see one on my dyno sheet for my old build.

[popo8]

Im running a 6al on mine

[95ImpySS]

Good thinking. I have a MSD Blaster coil. But no ignition box. Guess i'll try out my digi 6 and see what happens. The car it was planned for is up for sale any way.

Here is the DataMaster log of the first dyno pull. http://www.freefilehosting.net/dyno1
Has some struggling, trying to find where to mat the gas without downshifting.

Here is the 2nd DataMaster log. http://www.freefilehosting.net/dyno2 This one is where the car was taken to red line. And the problem is most prevalent.

Thanks for the replys!!!

[zooguy]

http://i97.photobucket.com/albums/l236/project95neon/dyno-1.jpg
this was my first pull with a completely stock car

http://i97.photobucket.com/albums/l236/project95neon/DynoSheet-1.jpg

after my last pull before i did my bigger stall and changed my exhaust to a true dual exhaust set up.

[95ImpySS]

Still hunting this dang problem. Does anyone know of a way to test spark plug wires? I can do a resisstance check, but from what I have read, as combustion pressures increase, resistance also increases. According to this thread: http://ls1tech.com/forums/lt1-lt4-modifications/1542226-high-rpm-miss-ive-had-years-i-cant-figure-out.html
One member had a similar issue, where the miss happened right where the car peaked in power. Higher combustion pressures = more power, thus more resistance on the wires?? The car does fall on its face right when it starts pulling hard...

I don't want to start changing parts left and right. Spent too much on the build already.

I am pretty convinced its an ignition related problem. Installing a MSD Digital 6 has yielded no improvement.
Some people say it could be

The opti (I'm running a reman sensor, with CMS cap + rotor new AC Delco awaiting reseal & install)
The plug wires. (Taylor is suppose to suck. From experience I can confirm. Car has a 2nd set of Taylors on it now)
EMI from crappy plug wires messing with the electronics.
Spark plug gap to large. Compression blowing the spark out. (Doubt it, cars 11:1 with NGK TR55's .48 gap)
Coil. (have old MSD Blaster. Will swap a replacement on since I have about 15 :) )
Weak ICM??? Bwaah?


I need to take the car in for a Dyno Tune since the mail order is not working out. But I don't want to take it there with a miss, ya know.

HALP!!

[firebird_1995]

I had a problem once with losing power on the top end. I went from Taylor wires and ngk tr55's at .050 to msd wires and ngk tr6's gapped at .038 and noticed a huge improvement.

[bigtoyz]

the msd muit spark boxes are causing a problem? I have one 6AL and it burnt out once but they fixed it ...........wondering if I should be taking that out. And also have a BTM hooked up after it.

And when my stock opti went out it was at 3600 it started to act up. And from the issue of my buddies have had with theirs...seems like a quite high rpm for an opti to be having problems at. Usually at mid range when the load gets put to it.